TPM error path on probe

[Tim Harvey]

Greetings,

Commit 481c2d14627d ("tpm,tpm_tis: Disable interrupts after 1000
unhandled IRQs") introduced a kernel warning for boards that do not
have a TPM loaded but have one defined in the device-tree (ie a
subloaded board assembly):

[    2.434431] WARNING: CPU: 3 PID: 55 at kernel/workqueue.c:3397
__flush_work.isra.0+0x2ac/0x2d8
[    2.443069] Modules linked in:
[    2.446133] CPU: 3 PID: 55 Comm: kworker/u8:3 Not tainted
6.6.8-00021-g232153790aa6-dirty #434
[    2.454758] Hardware name: Gateworks Venice GW73xx-2x i.MX8MP
Development Kit (DT)
[    2.462337] Workqueue: events_unbound async_run_entry_fn
[    2.467669] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[    2.474647] pc : __flush_work.isra.0+0x2ac/0x2d8
[    2.479278] lr : flush_work+0x10/0x1c
[    2.482950] sp : ffff80008270ba40
[    2.486271] x29: ffff80008270ba40 x28: 00000000ffffffff x27: 00000000ffffffff
[    2.493425] x26: ffff000000293000 x25: ffff80008218aff8 x24: ffff800080a1c6a8
[    2.500578] x23: 00000000ffffffff x22: ffff80008213ca18 x21: 0000000000000001
[    2.507731] x20: ffff000000e142c0 x19: ffff000000e14280 x18: 0000000000000000
[    2.514884] x17: 0000000000000000 x16: 000000000000001c x15: 0000000000000000
[    2.522038] x14: ffff00003fd94100 x13: 0000000000000002 x12: 0000000000000000
[    2.529191] x11: 0000000000000400 x10: 0000000000000910 x9 : 00000000ffffffff
[    2.536346] x8 : 0000000000000cc1 x7 : ffff8000804c76d8 x6 : 00000000090ee8ad
[    2.543500] x5 : ffff00000026c380 x4 : 0000000000000000 x3 : 0000000000000000
[    2.550655] x2 : 0000000000000000 x1 : ffff00000026c380 x0 : 0000000000000000
[    2.557806] Call trace:
[    2.560261]  __flush_work.isra.0+0x2ac/0x2d8
[    2.564544]  flush_work+0x10/0x1c
[    2.567869]  tpm_tis_remove+0x8c/0xc4
[    2.571545]  tpm_tis_core_init+0x194/0x7b8
[    2.575656]  tpm_tis_spi_probe+0xa4/0xd4
[    2.579593]  tpm_tis_spi_driver_probe+0x34/0x64
[    2.584136]  spi_probe+0x84/0xe4
[    2.587377]  really_probe+0x148/0x2c0
[    2.591052]  __driver_probe_device+0x78/0x12c
[    2.595417]  driver_probe_device+0xd8/0x15c
[    2.599609]  __device_attach_driver+0xb8/0x134
[    2.604064]  bus_for_each_drv+0x84/0xe0
[    2.607913]  __device_attach_async_helper+0xac/0xd0
[    2.612808]  async_run_entry_fn+0x34/0xe0
[    2.616832]  process_one_work+0x138/0x260
[    2.620851]  worker_thread+0x32c/0x438
[    2.624609]  kthread+0x118/0x11c
[    2.627844]  ret_from_fork+0x10/0x20
[    2.631428] ---[ end trace 0000000000000000 ]---

The issue is caused by tpm_tis_remove() calling flush_work() on the
work queue that has not yet been initialized. I can move the INIT_WORK
call added in this commit into the probe to fix this:
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index d5ea22196b5b..e62294b3a437 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -1133,6 +1133,8 @@ int tpm_tis_core_init(struct device *dev, struct
tpm_tis_data *priv, int irq,

        dev_set_drvdata(&chip->dev, priv);

+       INIT_WORK(&priv->free_irq_work, tpm_tis_free_irq_func);
+
        rc = tpm_tis_read32(priv, TPM_DID_VID(0), &vendor);
        if (rc < 0)
                return rc;
@@ -1159,8 +1161,6 @@ int tpm_tis_core_init(struct device *dev, struct
tpm_tis_data *priv, int irq,
                }
        }

-       INIT_WORK(&priv->free_irq_work, tpm_tis_free_irq_func);
-
        if (chip->ops->clk_enable != NULL)
                chip->ops->clk_enable(chip, true);

However I wonder if we should simply have error checking for an
invalid vendor of 0xffffffff. Is there any reason to not return an
-ENODEV if vendor == 0xffffffff?

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index d5ea22196b5b..1bb1b3e1b2d0 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -1136,6 +1136,8 @@ int tpm_tis_core_init(struct device *dev, struct
tpm_tis_data *priv, int irq,
        rc = tpm_tis_read32(priv, TPM_DID_VID(0), &vendor);
        if (rc < 0)
                return rc;
+       if (rc == 0xffffffff)
+               return -ENODEV;

        priv->manufacturer_id = vendor;

I'm not sure if a hard coded 0xffffffff check is best here.

Best regards,

Tim